Samples of Hydractinia were collected from the South China Sea.Two new species of H.constrictura sp.nov.and H.phyllosoma sp.nov.are described in the present paper.The specific diagnosis of the two new species is as follows:Hydractinia constrictura sp.nov.Umbrella global-shaped,without apical projection; manubrium long,with a whorl slightly constriction in nearly middle part of manubrium,which is divided into two parts,with vacuolated endodermal cells scattered in upper part of manubrium and no vacuolated cells in lower part; with 4 perradial oral arms,unbranched,each termination with a single knob-shaped cluster of cnidocysts; gonads interradial on manubrium,with medusa buds; with 4 marginal tentacles,bulb global,ending in a large cnidocyst knob.Hydractinia phyllosoma sp.nov.Umbrella bell-shaped,without apical projection; without gastric peduncle,manubrium short; mouth quadrate,with 4 leaf-like lips with cnidocyst clusters; gonads interradial on manubrium,without medusa buds; 4 marginal tentacles.